The invention relates to a separating device and to a method for separating solids, such that coarse solid constituents are separated from fine solid constituents.
In many fields in the industry, it is necessary to separate solids, which are contained, for example, in bulk material, into a plurality of constituents or fractions. The constituents are, as a rule, subdivided according to different sizes, geometries, or compositions. A separation of the solids is desirable whenever the different solid constituents are provided for further treatment.
In the building industry, for example, building debris is separated from large and bulky debris constituents which can then be sorted and reutilized. The separated finer building debris is disposed of, for example, on a dump provided for this purpose.
In the field of waste disposal, the separation and sorting of the waste or of residues occurring during waste utilization are of increasing importance in view of a disposal which protects the environment as much as possible. An essential factor in this is separation of the waste according to its size. Separation may be carried out before the waste is utilized; however, it may also be an essential method step during waste utilization itself.
For waste elimination, thermal methods are known, in which the waste is burnt in refuse incineration plants or is pyrolyzed in pyrolysis plants, that is to say subjected to a temperature of about 400xc2x0 C. to 700xc2x0 C. with the exclusion of air. In both methods, it is expedient to separate the residue remaining after incineration or after pyrolysis, in order either to supply it for reutilization or to dispose of it in a suitable way. In this case, the aim is to keep the residue to be ultimately stored on a dump as low as possible.
European Patent EP 0 302 310 and the company publication xe2x80x9cDie Schwel-Brenn-Anlage, eine verfahrensbeschreibungxe2x80x9d [xe2x80x9cThe Low-Temperature Carbonization Incineration Plant, a Process Descriptionxe2x80x9d], published by Siemens A G, Berlin and Munich, 1996, disclose as a pyrolysis plant, a so-called low-temperature carbonization incineration plant, in which essentially a two-stage method is carried out. In the first stage, the waste delivered is introduced into a low-temperature carbonization drum (pyrolysis reactor) and is carbonized at low temperature (pyrolyzed). During pyrolysis, low-temperature carbonization gas and pyrolysis residue form in the low-temperature carbonization drum. The low-temperature carbonization gas is burnt, together with combustible parts of the pyrolysis residue, in a high-temperature combustion chamber at temperatures of approximately 1200xc2x0 C. The waste gases occurring in the process are subsequently purified.
The pyrolysis residue also has non-combustible constituents in addition to combustible parts. The non-combustible constituents are composed essentially of an inert fraction, such as glass, stones or ceramic, and of a metal fraction. The useful materials of the residue are sorted out and recycled. For sorting purposes, it is necessary to have methods and components which ensure reliable and continuous operation.
In the case of screening or separating devices, there is often the problem that the screen surfaces become clogged. The separating device then breaks down or has to undergo, at least, complicated and labour-intensive cleaning. The problem of the blockage of separating devices arises, in particular, when the solids to be separated have a highly inhomogeneous composition. Thus, for example, wires catch in perforated plates used as screen surfaces, so that the individual holes S are initially narrowed and, in time, become clogged. Moreover, for specific uses, the separated solid fragments should not exceed a maximum size.
The residue occurring during pyrolysis is typically a highly inhomogeneous solid of this kind, which has pronounced differences as regards its material composition, its size and the geometry of its solid fragments. The residue also contains, in addition to stones, broken glass and larger metal fragments, elongate bars or entangled wires (wire pellets).
It is accordingly an object of the invention to provide a separating device and a method for separating solids, which overcome the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which allow a continuous operation with simple measures and which ensure that only solid constituents up to a maximum dimension are separated.
With the foregoing and other objects in view there is provided, in accordance with the invention, a separating device for separating solids, including:
at least two deflecting rollers;
a moving belt rotating about the at least two deflecting rollers, the moving belt defining a conveying direction;
transverse strips or plates fastened to the moving belt, the transverse strips being spaced from one another and extending transversely to the conveying direction, the transverse strips defining fall-through orifices for solids, the fall-through orifices defining a plane; and
a feed device for feeding the solids, the feed device being configured such that the solids are deposited at an acute angle, substantially parallel to the plane defined by the fall-through orifices.
Only solid fragments, the dimension of which is smaller than that of the fall-through orifices, fall through the fall-through or screening orifices. Larger solid fragments remain lying on the transverse strips and, lying on these, are transported further to the end of the separating device. The moving belt is preferably very narrow and serves primarily for the forward movement and the fastening of the transverse strips, which are provided, in particular, vertically on the moving belt, so that they form an elevation. For example, two moving belts are provided, which run parallel and next to one another and on which the transverse strips are fastened. The fall-through orifices are therefore delimited by the moving belts and by the transverse strips.
The particular advantage of the separating device is that a solid constituent or fraction, the dimension of which corresponds to the spacing between two successive transverse strips and which has been jammed between them, is automatically released at the end of the separating device in the region of the end-face deflecting roller. This is because, during rotation around the deflecting roller, the spacing between the two transverse strips widens and allows the solid fragment to fall down. The possibility of a blockage of the separating device is thus eliminated and continuous fault-free operation is ensured.
The separating device advantageously has a feed device for the solids, via which the solids can be applied essentially parallel to the plane formed by the fall-through orifices. For this purpose, the feed device preferably terminates directly above the moving belt, and its feed direction forms an acute angle with the conveying direction.
The solid fragments or constituents, in particular elongate solid fragments, supplied to the separating device are therefore fed, approximately parallel, to the plane formed by the fall-through orifices. This rules out the possibility of such elongate solid fragments falling vertically through the fall-through orifices.
Moreover, the configuration of the feed device directly above the moving belt or above the transverse strips prevents the parallel-aligned solid fragments from tilting vertically downwards and falling lengthways through the fall-through orifices. The smaller the acute angle of the feed device is, the more reliably elongate solid fragments are correctly separated according to their length. The feed direction may also run parallel to the conveying direction, in so far as the, for example, horizontally provided feed device has a separate conveying device, so that the solids can be supplied to the separating device, or in so far as the entire separating device, together with a feed device, is inclined relative to the horizontal.
For the alignment of elongate solid fragments, it is expedient, in particular, if an impermeable bottom is provided directly below the upper portion of the moving belt, the upper portion facing the feed device.
Elongate solid fragments striking the separating device at an angle first hit the impermeable bottom with their front end and cannot fall through lengthways. They remain lying, together with other large solid fragments, on the transverse strips and are transported further as far as the end of the separating device. The fine solids accumulate in the region of the bottom and are pushed forwards by the transverse strips to the fall-through orifice which follows in the conveying direction and through which the fine solids fall. They are preferably transported away by a conveying device which is provided adjacent to the impermeable bottom.
A particularly advantageous embodiment has, between two successive transverse strips, at least one longitudinal strip or plate which is fastened to one transverse strip and which reaches as far as the other transverse strip. The longitudinal strip brings about a further subdivision of the fall-through orifices.
In order to allow the solids to be screened uniformly into two different size constituents, such that the solid fragments of the separated fine constituent do not exceed a maximum size, screen surfaces of equal size are formed by the transverse strips and longitudinal strips. For this purpose, the transverse strips and the longitudinal strips are in each case provided equidistantly.
Provided in each case on those end faces of the longitudinal strips which point away from the moving belt is a strip having a width greater than the thickness of the longitudinal strip, so that the strip overlaps its longitudinal strip.
The configuration of the strips on the longitudinal strips ensures that solid fragments cannot be jammed between the longitudinal strips, that is to say parallel to the transverse strips. A jamming cannot occur due to the overlap of the strips, in other words, because the spacing between two longitudinal strips is always greater than the spacing between the strips which are provided on the corresponding longitudinal strips. Solid fragments can be jammed only between the strips, but not between the longitudinal strips.
In order to prevent solid fragments from being jammed on those end faces of the transverse strips which point away from the moving belt, the strips are configured to be step-shaped, the lower portion of a strip being fastened to one of the longitudinal strips, and the upper portion partially overlapping the strip of the following longitudinal strip.
In a further preferred version, there is provided on that side of the separating device which is located opposite the feed device, in particular at the lower reversal point of the moving belt, a cleaning rake which is aligned essentially parallel to the transverse strips and the tines of which engage into the interspaces formed by the longitudinal strips. With the aid of the rake, solid fragments which have been jammed between the strips can therefore be effectively removed.
In order to avoid excessive stress or forces on the rake, the latter is preferably provided in such a way that it pivots away when the force exerted on it exceeds a specific value. This prevents a very tightly jammed solid fragment from damaging the rake. In a further preferred version, if the force exerted is exceeded, this not only causes the cleaning rake to be tilted away, but, at the same time, switches off the separating device, so that the jammed solid fragment may, under certain circumstances, be removed manually, and damage to the separating device is prevented.
For a particularly robust version of the separating device, the moving belt is configured as a chain and, in particular, the longitudinal strips and transverse strips are made of metal.
According to another feature of the invention, the chain has chain links and the transverse strips are fastened centrally to respective ones of the chain links such that a spacing between two of the transverse strips is smaller at the deflecting rollers on a side facing towards the deflecting rollers than the spacing between the two of the transverse strips at a point upstream from, in other words in front of, the deflecting rollers.
According to yet another feature of the invention, the transverse strips are releasably fastened to the respective ones of the chain links.
According to another feature of the invention, the at least two deflecting rollers include at least a feed-side deflecting roller, a discard-side deflecting roller, and a bottom deflecting roller downstream of the discard-side deflecting roller, and the transverse strips have a first angle of spread at the discard-side deflecting roller and a second angle of spread at the bottom deflecting roller, the first angle of spread being smaller than the second angle of spread.
According to a further feature of the invention, the at least two deflecting rollers include a discard-side deflecting roller having a stripper for preventing the solids from falling onto,the discard-side deflecting roller. The stripper is preferably an elastic stripper.
According to another feature of the invention, the moving belt has a transport region for transporting the solids; and a guide strip is provided for preventing the moving belt from sagging in the transport region.
With the objects of the invention in view there is also provided, a method for separating solids, the method includes the steps of:
providing a separating device having transverse strips fastened to a moving belt guided about deflecting rollers such that the transverse strips define fall-through orifices;
feeding solids to the separating device by depositing the solids at an acute angle, substantially parallel to a plane defined by the fall-through orifices;
separating fine solids by letting the fine solids fall through the fall-through orifices between the transverse strips;
collecting the fine solids and transporting the fine solids away with a first conveying device;
transporting coarse solids, lying on the transverse strips, in the conveying direction as far as an end-face deflecting roller; and
collecting and transporting the coarse solids away with a second conveying device.
In other words, with regard to the method, the object of the invention is achieved, in that solids are fed to a separating device having a moving belt. The solids are deposited at an acute angle, substantially parallel to a plane defined by fall-through orifices. The solids are guided via deflecting rollers, and transverse strips mounted on the moving belt, fine solids falling through the fall-through orifices between the transverse strips and being collected and led away by a first conveying device, and coarse solids being transported, lying on the transverse strips, in the conveying direction as far as the end-face deflecting roller and being collected there by a second conveying device and being led away.
The advantageous embodiments presented with regard to the separating device apply accordingly to the method.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a separating device for solids and a method for separating solids, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.